The Beam Forming (BF) is based on the principle of adaptive antenna and each antenna unit is weighted respectively utilizing the antenna array according to the advanced signal processing algorithm, so as to make the array align in real time the useful signal direction and form the interference nulling in the interference direction to suppress the interference signal. FIG. 1 is a schematic diagram illustrating a beamforming system. The use of the beamforming technology can improve the signal to noise ratio, and improve the system performance and extend the coverage of the system.
The single transmitting end MIMO is a communication system in which a plurality of antennas are disposed respectively on the transmitting end and the receiving end. As shown in FIG. 2, the encoding modes thereof are mainly divided into two types: the space diversity and the space multiplexing. When the transmitting end or the receiving end has a plurality of antennas and data sets sent by the each transmitting antenna are the same, the receiving end merges the signals acquired from a plurality of branches and thus the reliability of the link is improved, and this type of MIMO technology is referred to as the space diversity. When both the transmitting end and the receiving end simultaneously have a plurality of antennas, because the MIMO channel is equivalent to a plurality of parallel channels, a plurality of data streams can be simultaneously transmitted in parallel and thus the transmission rate of the data is improved, and this is the space multiplexing.
The collaborative MIMO is an extension of the conventional single transmitting end MIMO technology. In the collaborative MIMO technology, a plurality of transmitting ends provide the services for a plurality of receiving ends on the same time-frequency resources by the collaboration, so as to achieve the purpose of reducing the interference between cells, improving the system capacity, improving the coverage of the cell boundaries and improving data rate of the receiving end, and the technology is very effective for improving the performance of the cell boundaries of the receiving end. The collaborative MIMO beamforming refers to a technology that each transmitting end adopts the beamforming in the collaborative MIMO system. As shown in FIG. 3, two transmitting ends provide service for the user located at the cell edge on the same time-frequency resources by way of the collaboration, so as to achieve the purpose of reducing the interference between the cells, thereby significantly improving data rate of the receiving end. As shown in FIG. 4, in order to implement the collaborative MIMO, the mutual collaborative transmitting ends need to communicate with each other, and functions of the resource scheduling and the MIMO encoding for data stream etc. are performed by a general controller.
In the cellular mobile communication system, the collaborative MIMO technology and the other single transmitting end MIMO technologies would co-exist, and it is also possible to require the mode switch between the different MIMO modes. And in the relevant art, the system is still configured as the fixed MIMO mode and subsequently still adopts the fixed MIMO mode to carry out the encoding and the transmission for the data steam, which would affect the flexibility of the collaborative MIMO system and would simultaneously cause the problem of decline of the system performance.